Characteristics and genesis of fractures in Middle Ordovician Majiagou Formation, Daniudi Gas Field, Ordos Basin
-
摘要: 鄂尔多斯盆地大牛地气田天然气潜力巨大,但中奥陶统马家沟组风化壳岩溶储层发育多种裂缝,成因复杂。为探明该储层裂缝特征,应用岩石学和测井技术,从裂缝发育频率、有效性、期次、赋存层位、形态、倾角等方面,比较了陡坎成因裂缝与构造裂缝的差异性;并通过弹性理论和断裂力学理论分析了裂缝端部区域的应力分量,探讨了陡坎裂缝的成因。陡坎成因裂缝以垂直缝、高角度斜交缝为主;裂缝延展方向和裂缝形态不规则,裂缝面不平整,具有上宽下窄、尾端无分叉特征;缝间有溶蚀现象,裂缝呈未—半充填状态,裂缝有效性高。陡坎成因裂缝受控于古地貌陡坡地形的坡度、岩层倾角、初始裂缝密度及岩石力学性质等因素;与构造裂缝相比,陡坎成因裂缝更有利于油气的运移。研究陡坎成因裂缝特征及成因,有助于进一步认识风化壳岩溶储层的展布规律,落实大牛地气田下一步勘探开发有利区。Abstract: The Daniudi Gas Field in the Ordos Basin has great natural gas potential, but a variety of fractures with complex origins was developed in the weathering crust karst reservoirs in the Middle Ordovician Majiagou Formation. In order to study the characteristics of fractures in the reservoirs, petrology and logging techniques were used to compare the differences between the fractures caused by steep ridges and structural fractures in terms of fracture development frequency, effectiveness, period, occurrence layer, shape, dip angle, etc. With elastic theory and fracture mechanics theory, the stress component at the end of fractures was analyzed, and the cause of the steep ridge fractures was discussed. Results show that the fractures caused by steep ridges are mainly vertical fractures and high-angle fractures. The fracture extension direction and fracture shape are irregular, and the fracture surface is uneven, with the characteristics of wide top and narrow bottom, and no bifurcation at the tail end. There is dissolution between the fractures, which is in a non- to semi-filled state, and the effectiveness of the fractures is high. The steep ridge fractures were controlled by factors such as ancient steep slope angle, rock layer inclination, initial fracture density and rock mechanical properties. Compared to structural fractures, the steep ridge fractures are more favorable for hydrocarbon migration. Studying the characteristics and causes of steep ridge fractures will help to further understand the distribution of weathered crust karst reservoirs, and identify favorable areas for the next exploration and development of the Daniudi Gas Field.
-
Key words:
- steep ridge fracture /
- fracture origin /
- Majiagou Formation /
- Middle Ordovician /
- Daniudi Gas Field /
- Ordos Basin
-
图 1 鄂尔多斯盆地大牛地气田中奥陶统马家沟组构造裂缝特征
a.区域构造应力缝(D39井,2 899.46~2 899.63 m),岩石发生剪切破裂形成的高角度或近垂直的裂缝,缝面形态规则;b.层面滑移缝(D53井,3 013.80 m),沿着软弱面顺层滑动产生,具有擦痕现象;c.基底断层复活派生裂缝(D92井,2 967.24~2 967.30 m),地层底部早期存在基底断层,后期基底断层差异复活,形成与低幅褶皱或断层派生的高角度张性缝或张剪性缝
Figure 1. Characteristics of structural fractures in Middle Ordovician Majiagou Formation, Daniudi Gas Field, Ordos Basin
表 1 鄂尔多斯盆地大牛地气田中奥陶统马家沟组陡坎成因裂缝与构造裂缝特征对比
Table 1. Characteristics of steep ridge and structural fractures in Middle Ordovician Majiagou Formation, Daniudi Gas Field, Ordos Basin
项目 构造裂缝 陡坎成因裂缝 发育频率 24.1% 24.6% 成因期次 印支、燕山和喜马拉雅构造运动 继承早期裂隙,后期派生拉张应力等诱发 赋存层位 马五1、马五2及马五5上部地层 马五3、马五4、马五5下部和马五6 裂缝形态 形态规则,延伸规模一致(图 1a) 形态不规则,延伸规模大小不等 缝面特征 见擦痕、阶步等现象(图 1b) 上宽下窄,不平整、局部弯曲,尾端无分叉 岩心上裂缝延伸长度/cm 0~10 0~40 岩心上裂缝张开度/cm 0~0.4 0~0.8 组系 平行组系(图 1c),倾角分布广泛 主要为垂直缝,高角度斜交缝次之 充填性 充填程度高 未充填和半充填状态为主 充填物 主要为方解石 方解石、白云石、砂泥质及石英等矿物 有效性 低 高 表 2 鄂尔多斯盆地大牛地气田中奥陶统马家沟组不同裂缝长度(2a)下的临界拉张应力值(σc)
Table 2. Critical tensile stress values (σc) for different values of crack length (2a), Middle Ordovician Majiagou Formation, Daniudi Gas Field, Ordos Basin
项目 参数 裂隙长(2a)/m 0.25 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 两条裂隙的中点距离(ω)/m 4.937 5 4.875 0 4.750 0 4.625 0 4.500 0 4.375 0 4.250 0 4.125 0 4.000 0 连通率(k)/% 6.25 12.50 25.00 37.50 50.00 62.50 75.00 87.50 100.00 临界拉张应力(σc)/MPa 8.65 8.56 8.44 8.21 7.84 7.27 6.39 4.89 0.30 表 3 鄂尔多斯盆地大牛地气田中奥陶统马家沟组地层陡坎成因裂缝判别标准
Table 3. Classification standards of fractures caused by steep ridges in Middle Ordovician Majiagou Formation, Daniudi Gas Field, Ordos Basin
分析方法 判别标准 岩心观察法 形态不规则,延伸规模大小不等;上宽下窄,裂缝面曲折、不平整、局部弯曲,尾端无分叉;缝间具有明显的溶蚀现象;延伸长度大,分布范围为0~40 cm;张开度大,分布范围为0~0.8 cm;裂缝有效性高 岩心薄片法 裂缝宽度较大,大于400 μm的占比为52.4%;裂缝面曲折,成网状,裂缝延展方向和裂缝形态不规则;常表现为一束主要破裂叠加多条树枝状分枝;缝间溶蚀现象明显 成像测井法 裂缝形态为混乱的、不连续的暗色—亮色影像;具有与溶蚀孔洞伴生的特点;裂缝张开度变化大,裂缝形态不规则;具有单周期的正弦曲线等构造裂缝的特征;走向分布杂乱,走向分布没有明显特征 表 4 鄂尔多斯盆地大牛地气田二级古地貌单元划分标准
Table 4. Classification standards of secondary paleomor-phological units in Daniudi Gas Field, Ordos Basin
地貌单元 开壳层位 马五1-4厚度范围/m 岩溶高地 马五14 >100 残丘(剥蚀区) 马五31 75~100 斜坡 马五22 50~75 沟槽 马五31 <50 注:表中数据据雷涛等[22]修改。 -
[1] 张冲. 大牛地气田奥陶系岩溶储层裂缝特征、成因及分布评价[D]. 成都: 成都理工大学, 2015.ZHANG Chong. The fracture characteristics, causes and distributionevaluation of the Ordovician karst reservoir in Daniudi Gas Field[D]. Chengdu: Chengdu University of Technology, 2015. [2] 张家伟, 王贵生, 刘慧, 等. 大牛地气田D66井区气井动态储量计算[J]. 重庆科技学院学报(自然科学版), 2015, 17(4): 77-79. https://www.cnki.com.cn/Article/CJFDTOTAL-CQSG201504021.htmZHANG Jiawei, WANG Guisheng, LIU Hui, et al. Calculation of dynamic reserves in D66 area of Daniudi Gas Field[J]. Journal of Chongqing University of Science and Technology (Natural Sciences Edition), 2015, 17(4): 77-79. https://www.cnki.com.cn/Article/CJFDTOTAL-CQSG201504021.htm [3] 孙晓, 王杰, 陶成, 等. 鄂尔多斯盆地大牛地下古生界天然气地球化学特征及其来源综合判识[J]. 石油实验地质, 2021, 43(2): 307-314. doi: 10.11781/sysydz202102307SUN Xiao, WANG Jie, TAO Cheng, et al. Evaluation of geochemical characteristics and source of natural gas in Lower Paleozoic, Daniudi area, Ordos Basin[J]. Petroleum Geology & Experiment, 2021, 43(2): 307-314. doi: 10.11781/sysydz202102307 [4] 苏中堂, 陈洪德, 欧阳征健, 等. 鄂尔多斯地区马家沟组层序岩相古地理特征[J]. 中国地质, 2012, 39(3): 623-633. https://www.cnki.com.cn/Article/CJFDTOTAL-DIZI201203007.htmSU Zhongtang, CHEN Hongde, OUYANG Zhengjian, et al. Sequence-based lithofacies and paleogeography of Majiagou Formation in Ordos Basin[J]. Geology in China, 2012, 39(3): 623-633. https://www.cnki.com.cn/Article/CJFDTOTAL-DIZI201203007.htm [5] 罗清清, 刘波, 姜伟民, 等. 鄂尔多斯盆地中部奥陶系马家沟组五段白云岩储层成岩作用及孔隙演化[J]. 石油与天然气地质, 2020, 41(1): 102-115. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT202001011.htmLUO Qingqing, LIU Bo, JIANG Weimin, et al. Diagenesis and pore evolution of dolomite reservoir in the 5th member of Ordovician Majiagou Formation, central Ordos Basin[J]. Oil & Gas Geology, 2020, 41(1): 102-115. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT202001011.htm [6] 丁晓琪, 刘鑫, 祁壮壮, 等. 碳酸盐岩孔洞型储层分层次储集空间表征: 以鄂尔多斯盆地大牛地中奥陶统马家沟组马五7为例[J]. 石油实验地质, 2021, 43(4): 689-696. doi: 10.11781/sysydz202104689DING Xiaoqi, LIU Xin, QI Zhuangzhuang, et al. Reservoir space characterization of vuggy carbonate reservoirs with multiple scales: a case study of Ma 5-7 interval, Middle Ordovician Majiagou Formation, Daniudi area, Ordos Basin[J]. Petroleum Geology & Experiment, 2021, 43(4): 689-696. doi: 10.11781/sysydz202104689 [7] 刘梅, 丁晓琪, 万友利, 等. 鄂尔多斯盆地大牛地气田奥陶系风化壳储层特征及分布[J]. 海相油气地质, 2014, 19(1): 35-42. https://www.cnki.com.cn/Article/CJFDTOTAL-HXYQ201401009.htmLIU Mei, DING Xiaoqi, WAN Youli, et al. Characteristics and distribution of Ordovician weathering crust reservoirs in Daniudi Gas Field, Ordos Basin[J]. Marine Origin Petroleum Geology, 2014, 19(1): 35-42. https://www.cnki.com.cn/Article/CJFDTOTAL-HXYQ201401009.htm [8] 李斌. 公路工程地质[M]. 2版. 北京: 人民交通出版社, 2002.LI Bin. Highway engineering geology[M]. 2nd ed. Beijing: China Communications Press, 2002. [9] 谢亚军, 朱勇辉, 国小龙. 土坝溃决研究进展及存在问题[J]. 长江科学院院报, 2013, 30(4): 29-33. https://www.cnki.com.cn/Article/CJFDTOTAL-CJKB201304007.htmXIE Yajun, ZHU Yonghui, GUO Xiaolong. Advances and problems in earth-dam failure research[J]. Journal of Yangtze River Scientific Research Institute, 2013, 30(4): 29-33. https://www.cnki.com.cn/Article/CJFDTOTAL-CJKB201304007.htm [10] 陈立官, 王洪辉, 朱创业, 等. 川中香溪群中裂缝形成机理探讨[J]. 成都地质学院学报, 1992, 19(1): 25-33. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG199201004.htmCHEN Liguan, WANG Honghui, ZHU Chuangye, et al. Discussion on the mechanism of formation of the fractures in Xiangxi Group from the central part of Sichuan[J]. Journal of Chengdu College of Geology, 1992, 19(1): 25-33. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG199201004.htm [11] 周文. 裂缝性油气储集层评价方法[M]. 成都: 四川科学技术出版社, 1998.ZHOU Wen. Evaluation method of fractured oil and gas reservoir[M]. Chengdu: Sichuan Science and Technology Press, 1998. [12] 陈立官, 王洪辉, 陆正元, 等. 川南地区古岩溶与阳新统天然气局部富集关系的探讨[J]. 成都地质学院学报, 1992, 19(4): 99-106. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG199204014.htmCHEN Liguan, WANG Honghui, LU Zhengyuan, et al. Disscussion on the relationship between local gas accumulation and paleokarst in the Yangxin limestones in southern Sichuan[J]. Journal of Chengdu College of Geology, 1992, 19(4): 99-106. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG199204014.htm [13] 唐明远. 大牛地气田马五5白云岩储层特征及分布规律研究[J]. 石油地质与工程, 2017, 31(5): 29-32. https://www.cnki.com.cn/Article/CJFDTOTAL-SYHN201705008.htmTANG Mingyuan. Dolomite reservoir characteristics and distribution regularity of Ma5-5 reservoirs in Daniudi gasfield[J]. Petroleum Geology and Engineering, 2017, 31(5): 29-32. https://www.cnki.com.cn/Article/CJFDTOTAL-SYHN201705008.htm [14] 张冲, 周文, 谢润成, 等. 大牛地气田马五1-2致密碳酸盐岩储层平缓构造带裂缝预测[J]. 东北石油大学学报, 2014, 38(3): 9-17. https://www.cnki.com.cn/Article/CJFDTOTAL-DQSY201403003.htmZHANG Chong, ZHOU Wen, XIE Runcheng, et al. Fracture prediction of the Ma51-2 tight carbonate reservoir in gentle structure zone, Daniudi Gas Field[J]. Journal of Northeast Petroleum University, 2014, 38(3): 9-17. https://www.cnki.com.cn/Article/CJFDTOTAL-DQSY201403003.htm [15] 张歧. 靖边气田地层水分布特征及产水气井复产措施优选[D]. 西安: 西安石油大学, 2012.ZHANG Qi. The pattern of formation water and restoring-production-measure optimization of water-producing gas wells in Jingbian Gas Field[D]. Xi'an: Xi'an Shiyou University, 2012. [16] 刘勇. 哈山地区石炭系-二叠系裂缝发育特征与油气成藏关系[D]. 成都: 成都理工大学, 2015.LIU Yong. The relationship between fracture characteristics and hydrocarbon accumulation of the Carboniferous-Permian in Hashan region[D]. Chengdu: Chengdu University of Technology, 2015. [17] 郭璇, 钟建华, 徐小林, 等. 非构造裂缝的发育特征及成因机制[J]. 石油大学学报(自然科学版), 2004, 28(2): 6-11. https://www.cnki.com.cn/Article/CJFDTOTAL-SYDX200402001.htmGUO Xuan, ZHONG Jianhua, XU Xiaolin, et al. Development characteristics and genetic mechanism of the untectonic fracture[J]. Journal of the University of Petroleum, China, 2004, 28(2): 6-11. https://www.cnki.com.cn/Article/CJFDTOTAL-SYDX200402001.htm [18] 黄润秋, 张倬元, 王士天. 论岩体结构的表生改造[J]. 水文地质工程地质, 1994, 21(4): 1-6. https://www.cnki.com.cn/Article/CJFDTOTAL-SWDG404.000.htmHUANG Runqiu, ZHANG Zhuoyuan, WANG Shitian. The epigenetic modification of rock mass structure[J]. Hydrogeology & Engineering Geology, 1994, 21(4): 1-6. https://www.cnki.com.cn/Article/CJFDTOTAL-SWDG404.000.htm [19] 姜薇. 基于ABAQUS的船舶典型结构裂纹扩展模拟及分析研究[D]. 武汉: 华中科技大学, 2011.JIANG Wei. Simulation and analysis of crack propagation in typical ship structure based on the ABAQUS software[D]. Wuhan: Huazhong University of Science & Technology, 2011. [20] 吴国强, 张丽娟, 杨振周, 等. 塔里木盆地哈拉哈塘地区奥陶系储层古岩溶作用及其与裂缝的关系[J]. 石油实验地质, 2017, 39(6): 790-796. doi: 10.11781/sysydz201706790WU Guoqiang, ZHANG Lijuan, YANG Zhenzhou, et al. Paleokarstification of the Ordovician carbonate reservoirs and the relationship with fractures in the Halahatang area of Tarim Basin[J]. Petroleum Geology & Experiment, 2017, 39(6): 790-796. doi: 10.11781/sysydz201706790 [21] 李继岩. 多期构造裂缝发育充填特征及其主控因素: 以济阳坳陷平南潜山为例[J]. 沉积学报, 2020, 38(2): 420-428. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB202002016.htmLI Jiyan. Filling Characteristics and main controlling factors for the development of multi-phase structural fractures: a case of the Pingnan buried hill from Jiyang Depression[J]. Acta Sedimentologica Sinica, 2020, 38(2): 420-428. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB202002016.htm [22] 雷涛, 刘绪钢, 闫淑红. 大牛地气田奥陶系古地貌特征研究[J]. 天然气技术与经济, 2014, 8(1): 8-11. https://www.cnki.com.cn/Article/CJFDTOTAL-TRJJ201401004.htmLEI Tao, LIU Xugang, YAN Shuhong. Ordovician palaeogeomorphologic features of Daniudi Gasfield, Ordos Basin[J]. Natural Gas Technology and Economy, 2014, 8(1): 8-11. https://www.cnki.com.cn/Article/CJFDTOTAL-TRJJ201401004.htm [23] 王亚青, 林承焰. 山旺盆地山旺组重力滑动构造的发现及其意义[J]. 西北地质, 2008, 41(2): 110-114. https://www.cnki.com.cn/Article/CJFDTOTAL-XBDI200802018.htmWANG Yaqing, LIN Chengyan. Discovery of the gravity gliding tectonic of Shanwang Formation, Shanwang Basin[J]. Northwestern Geology, 2008, 41(2): 110-114. https://www.cnki.com.cn/Article/CJFDTOTAL-XBDI200802018.htm [24] 高飞. 利用地震正演及属性预测碳酸盐古沟槽、裂缝和孔溶洞: 以鄂尔多斯盆地甘泉地区马家沟组为例[J]. 非常规油气, 2019, 6(4): 25-32. https://www.cnki.com.cn/Article/CJFDTOTAL-FCYQ201904006.htmGAO Fei. Prediction of carbonateerosion flutes, fracture and cavity by seismic forward modeling and attributes: a case study of Majiagou Formation in Ganquan area of Ordos Basin[J]. Unconventional Oil & Gas, 2019, 6(4): 25-32. https://www.cnki.com.cn/Article/CJFDTOTAL-FCYQ201904006.htm [25] 黎静容, 朱桦, 冯晓明, 等. 川东北陆相储层裂缝特征差异性及对产能的影响[J]. 石油实验地质, 2016, 38(6): 742-747. doi: 10.11781/sysydz201606742LI Jingrong, ZHU Hua, FENG Xiaoming, et al. Differences of fracture characteristics and the influence on productivity in the northeastern Sichuan continental basin[J]. Petroleum Geology & Experiment, 2016, 38(6): 742-747. doi: 10.11781/sysydz201606742 [26] 兰叶芳, 邓秀芹, 程党性, 等. 鄂尔多斯盆地华庆地区长6油层组砂岩成岩相及储层质量评价[J]. 岩石矿物学杂志, 2014, 33(1): 51-63. https://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201401004.htmLAN Yefang, DENG Xiuqin, CHENG Dangxing, et al. Diagenetic facies and reservoir quality evaluation of Chang 6 sandstone reservoir in the Upper Triassic Yanchang Formation of Huaqing area, Ordos Basin[J]. Acta Petrologica et Mineralogica, 2014, 33(1): 51-63. https://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201401004.htm [27] 卢炳雄, 文华国, 淡永, 等. 准噶尔盆地阜康凹陷阜东斜坡齐古组储层控制因素及有利区预测[J]. 石油与天然气地质, 2018, 39(3): 549-557. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT201803013.htmLU Bingxiong, WEN Huaguo, DAN Yong, et al. Favorable accumulation region prediction and controlling factors of hydrocarbon accumulation of the Qigu Formation in the Fudong Slope, Fukang Sag, Junggar Basin[J]. Oil & Gas Geology, 2018, 39(3): 549-557. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT201803013.htm